Turbines intended for installation in locations having a constant fluid flow (i.e., locations in which the flow of the fluid that drives the turbine is generally uncontrollable, such as a river bed) are known in the art. Placing turbines in such locations is advantageous, since the constant supply of kinetic energy supplied by the constant fluid flow can be valuable, if harnessed.
Turbines intended for use in such locations generally comprise a housing that allows a portion of the flowing fluid to move an interior thereof. The fluid contacts paddles mounted on a rotor within the housing as it moves through, and causes the rotors to rotate. An output drive shaft of the rotor can be coupled to a driven element, such as an electrical generator, and the rotational motion of the rotor (which is ultimately generated by the movement of the fluid through the turbine) can be used to generate electricity or for other useful purposes.
Some turbines intended for use in locations having constant fluid flow encounter problems when the paddles of the rotor have to move against the flow of the fluid through the turbine, so that the rotor can complete its rotation. When this is the case, the kinetic energy of the fluid flow tends to reduce the amount of rotational energy produced by the turbine.
Another problem is encountered when such turbines must be taken out of service, for example, for maintenance purposes. Since the fluid flow through the turbine generally cannot be controlled, it can be difficult to stop the turbine rotors from rotating. A brake can be applied, but this solution results in a great deal of structural stress being applied to both the rotor and the components of the brake itself.